A calorimeter of water equivalent 20 g contains 180g of water at ${25}^0$C. ‘m’ grams of steam at ${100}^0$C is mixed in it till the temperature of the mixture is ${31}^0$C. The value of ‘m’ is close to (Latent heat of water = 540 cal $g^{-1}$, specific heat of water = 1 cal $g^{-1}$  ${ }^0{C}^{-1}$)

• A

  2

• B

  4

• C

  3.2

• D

  2.6